Textbook Solutions: Water | Eureka Plus Class 6: Book Solutions, Notes & Worksheets PDF Download

I. Tick (✔) the correct option/options.

1.
Ans: (d)

2. 
Ans: (b)

3. 
Ans: (c)

4. 
Ans: (b)

5. 
Ans: (c)

6. 
Ans: (a, b)

II. Answer the following questions in two to three sentences.

1.
Ans: Potable water is safe for human consumption and includes water from rivers, dams, lakes, wells, and groundwater resources.

2.
Ans: We must keep rivers, lakes, and groundwater resources clean to ensure a fresh and safe supply of drinking water and to prevent pollution-related health issues.

3.
Ans: Water exists in three states in nature: solid (snow, ice), liquid (rivers, ponds, oceans), and gaseous (water vapor in the air).

4.
Ans: Precipitation refers to rain or snowfall caused by the condensation of water vapor in the air, leading to the formation of clouds and subsequent release of water droplets.

5.
Ans: Rainwater harvesting is the collection and storage of rainwater for future use. It can be done by collecting rainwater from rooftops into tanks or allowing it to flow into pits for groundwater recharge.

6.
Ans: A check dam is a structure built to impede the flow of rainwater, collecting it in a designated area and allowing it to seep into the ground. It helps increase the availability of water in the region.

III. Replace each letter in capital with the correct word in each of the sentences given below.

1.
Ans: We must use only 'CLEAN' water for our daily consumption.

2.
Ans: Plants 'ABSORB' water through a process called 'TRANSPIRATION'.

3.
Ans: 'POLLUTED' water from industries and homes cannot be used to grow 'CROPS'.

4.
Ans: 'HYDROELECTRIC' power plants are built on dams to produce 'ELECTRICITY'.

5.
Ans: The 'UNDERGROUND' water that seeps deep into the 'ROCKS' and collects in the spaces between the 'SOIL' is called 'GROUNDWATER'.

6.
Ans: In 'COASTAL' regions, floods are often caused by severe ocean wind storms called 'CYCLONES'.

IV. Give reasons.

1.
Ans: Because three-fourths of the Earth's surface is covered with water, giving it a blue appearance from space.

2.
Ans: Because 97.5% of all water is in the oceans, and ocean water is salty and unsuitable for drinking.

3.
Ans: Because it is salty, and most plants cannot tolerate or thrive in salty conditions.

4.
Ans: Because water contaminated with harmful chemicals and microorganisms can adversely affect the health of plants and the safety of farm products.

5.
Ans: Because the air becomes cooler at higher altitudes, causing the water vapour to condense into tiny water droplets and form clouds.

6.
Ans: Because excess water accumulates in lakes and rivers, leading to overflow and inundation of surrounding areas.

V. Write a passage of about one and a half page on the following topics. Include diagrams. 

1. 
Ans: Groundwater, a vital source of fresh water, forms a significant part of the Earth's natural water cycle. As rainwater seeps through the soil, it percolates deep into the ground, filling the porous spaces in bedrock, creating aquifers. Groundwater is crucial for ecosystems and human settlements alike, supplying water to wells, springs, and rivers. It acts as a natural filter, purifying water as it trickles through layers of soil and rock, providing clean water that is often safe for drinking.

2.
Ans: Rainwater harvesting is an ancient and increasingly relevant method of collecting rainwater for future use. This process involves capturing rain from surfaces such as rooftops and directing it into storage tanks or allowing it to infiltrate into the ground to replenish aquifers. In regions with limited water resources, rainwater harvesting is a sustainable solution that reduces dependence on municipal water supplies, mitigates the effects of drought, and helps prevent flooding and erosion by controlling stormwater runoff.

3. 
Ans: Check dams play a pivotal role in water conservation, especially in arid and semi-arid regions. These small, sometimes temporary barriers are constructed across the width of seasonal streams. They slow the flow of water, promoting the infiltration of water into the ground, thereby recharging groundwater aquifers. This practice also helps in reducing soil erosion, retaining sediment, and managing flash flooding. By creating a reservoir of water, check dams ensure the availability of water during dry periods, supporting agriculture and providing habitats for local wildlife. Collectively, groundwater management, rainwater harvesting, and check dams constitute a multifaceted approach toward sustainable water resource management, essential for securing water for future generations.

Think and answer

1.
Ans: Srinagar is facing a shortage of clean drinking water primarily due to pollution. The Dal Lake, which is a significant source of water, has suffered from the introduction of sewage from houseboats and wastewater from hotels and homes. Furthermore, agricultural practices around the lake, including the use of pesticides, have contributed to the degradation of water quality. This pollution has affected the lake’s ecosystem, leading to a decline in fish varieties and bird populations. As the pollution makes the water unsafe, the once abundant clean water supply is now inadequate for consumption.

2.
Ans: The case study demonstrates this point by showing the direct impact on the lake's ecosystem, including the decline in fish and bird populations due to the contamination of the water with sewage and agricultural chemicals. The pollution has turned the lake's surface into an opaque green with duckweed, indicating a loss of biodiversity and a decline in water quality that affects all organisms relying on this habitat.

3.
Ans: To clean the lakes in Srinagar, a multi-faceted approach is needed. This includes preventing sewage and wastewater from entering the lakes, controlling agricultural runoff, and managing solid waste. Implementing effective sewage treatment plants, promoting organic farming practices to reduce pesticide usage, and regulating tourism to prevent overuse of resources are critical steps. Additionally, educating the public on the importance of water conservation and enforcing strict pollution control laws are necessary to restore and maintain the cleanliness of the lakes.